LINAC 14 27th Linear Accelerator Conference - JACoW (Indico)

LINAC 14 27th Linear Accelerator Conference Geneva, Switzerland, 31 Aug. - 5 Sept. 2014

LINAC 14 27th Linear Accelerator Conference Geneva, Switzerland, 31 Aug. - 5 Sept. 2014 2

Particles p+ D+ Ions

Q/A 1 1/2 1/3 1/6

I (mA) max. 5 5 1 1

WO min. (Mev/A) 2 2 2 2

WO max. (Mev/A) 33 20 14.5 8.5

CW max. beam power (KW) 165 200 44 48

Beam parameters of LINAC

CW accelerator driver of SPIRAL2 26 superconducting QWR cavities 2 families of cavities/cryomodules

Type A Type B


•Frequency of the pulses: 88.0525 MHz (period of bunches: ~11.36 ns)

•Phase extension of the bunch (±2 σ): 60 ° or ~1.9 ns for bunch length

•Period of macropulse: can vary between 100 μs and 1s

•The form factor is lay at range 4101

macropulce of period

length macropulce


• Provide measurements without beam perturbation

• Compact sized for installation at diagnostic box of LINAC

• Measurement time as short as possible

• Phase resolution 1°

• Operation at cryomodule vicinity (vacuum and cleanness conditions for BEM components)

Proper beam adaption of LINAC requires measurement of phase extension

Requirements of BEM diagnostics: Diagnostic box of LINAC equipped with BEM


X-ray emission due to ionization of the wire by impinging beam ions

Principal Characteristic X-Rays Energies for Tungsten

Values are from J. A. Bearden, "X-Ray Wavelengths", Review of Modern Physics, (January 1967) pp. 86-99

K Series L Series

Lines Kα1 Kα2 Kβ1 Lα1 Lα2 Lβ1 Lβ2 Lγ1

Energy, keV 59,32 57,98 67,24 8,40 8,34 9,67 9,96 11,29

Precise time measurements similar to Time-Correlated Single Photon Counting (TCSPC) technique

X-ray detector

System for wire insertion

5


Deflecting foil • suppression of residual gas ions • transparent for x-rays

Copper collimator Registration X-rays coming from the wire

Microchannel plates • assembled at chevron

configuration • provide 107-108 gain

N-type connector matched on 50Ω impedance for fast output pulse

Fast readout anode • short output signal with

400 psec risetime

500 psec/div

100 mV/div

Detector output signals for 5,9 keV x-ray source of 55Fe

6


Brushless motor • part of Siemens SINAMICS S110 system • positioning precision better than 100 µm

Conducting frame with tungsten wires • three holders with 150 µm wires for

quick replacement of damaged wire • electrically insulated for current pick-up

measurements from the wire

Alternate orientation of wires to minimize influence of neighboring BEMs to their measurements

7


stop

tungsten wire

collimator

MCP stack

coaxial anode e-

X-rays

negative HV

CFD

CFD

TAC

RF=88MHz

signal

start

MCA

PC

Deflecting foil

positive voltage

A

Technical room

LINAC tunnel

~55 meters

σ~6 psec time resolution for read out electronics

+

8


740 745 750 755 760 765 770 775 780

0

10

20

30

40

50

Ebeam

= 10MeV, cycle 1s

FWHM=5.67ns

Time, ns

0 5 10 15 20 25 30 35 40 45 50

0

20

40

60

80

100

Co

unts

Time (nsec)

Test of prototype with proton beam (10 MeV, 1.75 nA)

The first test shown high background related to residual gas ions

Test of BEM prototype with beam of 18O ions (1.26 MeV/A, 10 A)

Al foil of 10 µm thickness was placed before MCP entrance with applied positive voltage +30 Volts Signal to noise ratio is 10

9


One of the most important questions for BEM operation is X-ray emission from cavity

X-rays have broad range of energies up to value of maximal energy of dark currents electrons

Finite spectrum of characteristic x-rays for tungsten

Cavity

X-ray detector of BEM X-ray detector of BEM

Cavity

Position of wire

It is very complicated to assess in advance for x-ray emission (strongly different from one cavity to another)

The direct measurements are more preferable and can give clear results

10


Position of the

BEM

Cavity MB03 Cavity MB01

- Cleaning and preparation of BEM in ISO4 clean room - Insertion in warm section under portable ISO5 clean room

Two portable clean rooms over installation area

11


E_max ~ 1000 keV at nominal value 6,5 MV/m of field gradient

Spectrum of x-ray emission from cavity

6 MV/m

0 MV/m

CANBERRA BARA31 with SFDE probe

Detector: Geiger Müller, energy compensated from 40 keV to 1.25 MeV Measurement range: External low dose rate probe: 3 µSv/h to 100 mSv/h

0.1

1

10

100

1000

10000

100000

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Do

se r

ate

[u

Sv/h

]

Accelerating field [MV/m]

probe on beam axis

probe at cryomodule

Expon. (probe onbeam axis)

Dose rate measurements for cavity MB03

12


Position of

the BEM

0 1 2 3 4 5 6 7 8 9 10 11 12

0,01

0,1

1

10

100

Co

un

tra

te (

cp

s)

Accelerating field (MV/m)

MB01 without wire

MB01 wire inserted

0 1 2 3 4 5 6 7 8 9 10 11 12

0,01

0,1

1

10

100

Co

un

tra

te (

cp

s)

Accelerating field (MV/m)

MB03 without wire

MB03 wire inserted

Cavity MB03 Cavity MB01

This test has proven the possibility of operation of a BEM close to a cryomodule working at nominal gradient

13


Tests with the industrial commissioned BEM on SARAF linac (cavities similar to SPIRAL2 ones) Development of Command/Control interface for BEM and integration of BEM architecture into the LINAC Procurement, control and commissioning of the whole series of BEMs

Installation of the five BEMs into the LINAC warm sections, adjustment of parameters of associated electronics, bunch length measurements

The first industrially produced BEM has been commissioned with a X-rays source during last month and its characterization is in progress

14


New design of a bunch extension monitor has been developed

Prototype of this detector has been successfully tested with ions beams

Possibility of operation close to a cryomodule has been demonstrated

Full characterization of the first series BEM is in progress

15

LINAC 14 27th Linear Accelerator Conference - JACoW (Indico)

Documents

Transcript of LINAC 14 27th Linear Accelerator Conference - JACoW (Indico)